The present invention relates to active windshield antenna for power vehicles for ultra short and long medium short radio frequency. More particularly it relates to a windshield antenna which has a metallic frame of a windshield of a power vehicle, an antenna wire, and an antenna amplifier.
Windshield antennas of the above-mentioned general type are known in the art. A known windshield antenna has a metallic frame of a windshield of a power vehicle, an antenna wire, an antenna amplifier with two input terminals and an output conduit, wherein the antenna amplifier is arranged in the vicinity of the metallic frame and the antenna wire is arranged on or in the windshield. The first input terminal of the antenna amplifier is connected with a maximum short connecting conductor with one end of the antenna wire, whereas the second input terminal of the antenna amplifier is connected with the conductive frame which surrounds the windshield and the output conduit of the amplifier leads to a receiver.
With active windshield antennas it is known to receive all the wave regions (long, medium, short and ultra short waves), as with the standard antennas in power vehicles. It is advantageous here that by the integration of the antenna into the vehicle body such antennas satisfy much better than the standard rod antennas the specific requirements applied to the vehicle, such as mechanical rigidity, high service life, simple mounting, elimination of unnecessary air whirling. Active windshield antennas with the above described properties are disclosed, for example, in the German GM application G 7,808,489.6. It has been shown that a power vehicle antenna which is proposed here provides for extremely unsatisfactory receiving power in the event of vertically or circularly polarized waves of the polarization types frequently used for example in the United States for the ultra short radio broadcasting, whereas the receiving power in the ultra short region with horizontal polarization and in the long medium short region of the standard antenna is at least equivalent. Also, for an unobjectionable functioning of the antenna the predetermined position of the antenna amplifier is disadvantageous. A modification disclosed in the GM in the change of the terminal location leads especially in the ultra short wave region to worsening of the reception properties.